Processes for preparing .gamma.-halonitriles are replete in the art. For example, it has long been known that .gamma.-chlorobutylnitrile can be prepared by heating potassium cyanide in a water-ethanol solution with 1-chloro-3-bromo-propane. Organic Synthesis 8, 52-3 (1928). More recently, patents have issued that employ catalysis to facilitate .gamma.-halonitrile formation. Illustrative is Horrom (U.S. Pat. No. 3,118,926) wherein thionyl chloride and .gamma.-hydroxybutylamide were reacted under reflux conditions for 16 hours in the presence of a catalytic amount of pyridine. The art does not disclose the use of an onium salt catalyst in the preparation of .gamma.-halonitriles, although Erickson (U.S. Pat. No. 2,524,011) teaches the use of said catalyst in the preparation of .beta.-chloro-isobutylnitrile from hydrogen chloride and methacrylonitrile.
These teachings suffer from a number of deficiencies. Yields are generally low, some require the use of organic solvents, and others are hampered by large dinitrile formation. These deficiencies result in inefficient use of source material and require complicated, time consuming recovery techniques. In turn, waste problems and increased labor and capital costs are incurred.